This is another in an occasional series of posts dissecting the claims made by JunkScience purveyor Steven Milloy’s “100 things you should know about DDT.” What I find in this list is a lot of deception, misleading claims, and general unjustified vitriol. In this post I’m looking at Milloy’s point #10.
10. Rachel Carson sounded the initial alarm against DDT, but represented the science of DDT erroneously in her 1962 book Silent Spring. Carson wrote “Dr. DeWitt’s now classic experiments [on quail and pheasants] have now established the fact that exposure to DDT, even when doing no observable harm to the birds, may seriously affect reproduction. Quail into whose diet DDT was introduced throughout the breeding season survived and even produced normal numbers of fertile eggs. But few of the eggs hatched.” DeWitt’s 1956 article (in Journal of Agriculture and Food Chemistry) actually yielded a very different conclusion. Quail were fed 200 parts per million of DDT in all of their food throughout the breeding season. DeWitt reports that 80% of their eggs hatched, compared with the “control”” birds which hatched 83.9% of their eggs. Carson also omitted mention of DeWitt’s report that “control” pheasants hatched only 57 percent of their eggs, while those that were fed high levels of DDT in all of their food for an entire year hatched more than 80% of their eggs.
Considering Carson’s careful citing of studies on all sides of the issue, and her use of sources dating back 30 years and more, it would be difficult for her to have “represented the science of DDT erroneously.” Carson got the science right. Milloy doesn’t even get the quote of Carson right, however, deleting her main point, and editing it to set up a straw man argument which misleads unwary readers.
Carson represented the science faithfully. Milloy simply dissembles in his accusation that she got it wrong.
In fact, Carson offered more than 50 pages of citations to studies, virtually everything available on DDT and the other chemicals she wrote about, up to the time of publication. Carson had started working on the issue in 1948, and worked almost solely on the work that became Silent Spring between 1959 and the book’s publication. None of the studies she cited has been retracted. Most of the studies were determined to be accurate in follow-up studies.
I discuss this at some length, below the fold.
There are other powerful corroborations to the accuracy of Rachel Carson’s claims in Silent Spring.
For example, because the chemical and pesticide industry mounted a strong and expensive campaign to impugn the work of Ms. Carson, President Kennedy appointed a blue-ribbon panel of scientists to evaluate her work. The President’s Science Advisory Committee (PSAC) reported in 1963 that Ms. Carson’s science was solid. They recommended that the government act immediately to try to reduce the damage being wrought by DDT and other chemicals used unwisely.
Also, the U.S. Environmental Protection Agency was created in 1969, with jurisdiction over pesticides. After EPA was sued for failing to act against DDT and other synthetic pesticides, the agency conducted dozens of studies on the effects of pesticides in the wild. On the basis of those studies, in 1972 EPA issued an order suspending the registration of DDT for broadcast use, citing toxic effects of the chemical that multiplied over the long life of the chemical in the wild. Deletory effects were cited on beneficial insects, beneficial birds, beneficial fish and beneficial mammals.
Extensive hearings in an EPA administrative law proceeding in 1972 produced a lengthy hearing record dominated by submissions from the pesticide manufacturing industry. EPA’s administrative law judge ruled that DDT was, under law, legal to use, despite evidence of extensive environmental damage. Judge Edwin Sweeney determined that he did not have legal authority to rule otherwise. His ruling was appealed to EPA Administrator William Ruckelshaus, who overturned Sweeney’s ruling on the law, and instead pointed to the record Sweeney had accumulated that showed DDT damages wildlife and posed health risks to humans whose risk was then not established. Ruckelshaus ruled that EPA did in fact have the legal authority to suspend registration of DDT as an insecticide. Of course, Ruckelshaus’s decision was immediately challenged by pesticide manufacturers. The courts ruled EPA was correct.
So Carson’s work was corroborated by high-power panels of scientists at the time, and over the next ten years official regulatory actions further corroborated her conclusions.
Most telling is this simple fact: When DDT use stopped, the reproduction problems of the affected birds began to ease. Egg-shell thinning and other bird reproduction problems, especially among raptors, steadily decreased as the residual levels of DDT and DDT by-products decreased in the birds’ bodies. Birds which Carson suggested might be in decline due to chemical assault have sprung back since DDT has fallen out of their lives. The American symbol, the bald eagle, came off the Endangered Species list in early 2007, because its populations are now considered sustainable, and its numbers have returned to most traditional ranges in the U.S. from which they were absent in the 1960s and 1970s.
Can we reconcile Milloy’s claims with what Carson wrote? Yes, but when we do, we find it is Mr. Milloy who is playing fast and loose with the facts.
Milloy quotes Carson out of chapter 8 of Silent Spring, “And no birds sing.” Carson argued that bird populations were declining because chemicals used against against insects and for other purposes interrupt the reproduction of the birds. She noted that bird watchers recorded increasingly small populations of one-year-old birds, the fledglings that would mature to produce future generations. She noted several studies of different species of birds, in the wild and in the laboratory, which showed difficulties in getting young birds from egg to successful fledge.
Milloy carefully picks one of several studies Carson cites, and he misrepresents the study’s findings. In doing this, to an unwary reader he makes a case that Carson was being deceptive. She was not; but Milloy is, in leaving out critical details.
Remember, Carson says the birds don’t make it to maturity to breed, and so the species are in trouble.
Milloy responds by quoting Carson, but very selectively. Note that he does not seriously address Carson’s point, that birds are dying before they can mature and breed, and that several species are threatened by the phenomenon; note that instead he makes it appear as if Carson were concerned solely about hatch rates:
Carson wrote “Dr. DeWitt’s now classic experiments [on quail and pheasants] have now established the fact that exposure to DDT, even when doing no observable harm to the birds, may seriously affect reproduction. Quail into whose diet DDT was introduced throughout the breeding season survived and even produced normal numbers of fertile eggs. But few of the eggs hatched.” DeWitt’s 1956 article (in Journal of Agriculture and Food Chemistry) actually yielded a very different conclusion. Quail were fed 200 parts per million of DDT in all of their food throughout the breeding season. DeWitt reports that 80% of their eggs hatched, compared with the “control” birds which hatched 83.9% of their eggs. Carson also omitted mention of DeWitt’s report that “control” pheasants hatched only 57 percent of their eggs, while those that were fed high levels of DDT in all of their food for an entire year hatched more than 80% of their eggs.
Where Milloy stops quoting Carson, she starts to make her argument: Milloy failed to cite what Carson argued!
Carson actually wrote this (I highlight in blue the words Milloy quotes, he omits the rest, some of which I’ve noted in red):
On Mount Johnson Island [in the Susquehanna River] as well as in Florida, then, the same situation prevails — there is some occupancy of nests by adults, some production of eggs, but few or no young birds. In seeking an explanation, only one appears to fit all the facts. This is that the reproductive capacity of the birds has been so lowered by some environmental agent that there are now almost no annual additions of young to the race.
Exactly this sort of situation has been produced artificially in other birds by various experimenters, notably Dr. James DeWitt of the United State Fish and Wildlife Service [Carson's former agency; she probably knew DeWitt]. Dr. DeWitt’s now classic experiments on the effect of a series of insecticides on quail and pheasants have established the fact that exposure to DDT or related chemicals, even when doing no observable harm to the parent birds, may seriously affect reproduction. The way the effect is exerted may vary, but the end result is always the same. For example, quail into whose diet DDT was introduced throughout the breeding season survived and even produced normal numbers of fertile eggs. But few of the eggs hatched. “Many embryos appeared to develop normally during the early stages of incubation, but died during the hatching period,” Dr. DeWitt said. Of those that did hatch, more than half died within 5 days. In other tests in which both pheasants and quail were the subjects, the adults produced no eggs whatever if they had been fed insecticide-contaminated diets throughout the year. And at the University of California, Dr. Robert Rudd and Dr. Richard Genelly reported similar findings. When pheasants received dieldrin in their diets, “egg production was markedly lowered and chick survival was poor.” According to these authors, the delayed but lethal effect on the young birds follows from storage of dieldrin in the yolk of the egg, from which it is gradually assimilated during incubation and after hatching.
This suggestion is strongly supported by recent studies by Dr. Wallace and a graduate student, Richard F. Bernard, who found high concentrations of DDT in robins on the Michigan State University campus. They found the poison in all of the testes of male robins examined, in developing egg follicles, in the ovaries of females, in completed but unlaid eggs, in the oviducts, in unhatched eggs from deserted nests, in embryos within the eggs, and in a newly hatched, dead nestling.
These important studies establish the fact that the insecticidal poison affects a generation once removed from initial contact with it. Storage of poison in the egg, in the yolk material that nourishes the developing embryo, is a virtual death warrant and explains why so many of De Witt’s birds died in the egg or a few days after hatching.
Did you catch that? Milloy claims Carson was wrong because hatch rates of the DDT-fed group were close to the hatch rates of the control group. This is called “quote mining.” Milloy omits the very next three sentences including a direct quote from Dr. DeWitt:
“But few of the eggs hatched. “Many embryos appeared to develop normally during the early stages of incubation, but died during the hatching period,” Dr. DeWitt said. Of those that did hatch, more than half died within 5 days.
That changes the point a bit, doesn’t it?
- Carson cited at least three different studies representative of a series of studies that support her point; Milloy deals with only one. The studies Carson cited have been corroborated by dozens of others.
- Carson argued that DDT and related chemicals harm species by preventing young from reaching breeding age. Milloy claims Carson got the hatch rates wrong, but ignores the key point, the survival rates of fledglings.
- Carson notes that even when young birds develop fully in the egg, they often die before hatching, and that among those that do hatch, high numbers die within a week. Milloy is silent about this finding, apparently counting a dead hatchling as no problem.
- Carson cites the damage to the next generation. Milloy notes that DDT doesn’t immediately kill the present generation, rebutting no argument Carson made in this chapter.
I find Milloy’s argument dishonest. He omits Mrs. Carson’s key arguments. He omits important parts of the material he quotes. He omits the material that refutes his claims. His argument seems directed at fogging up the point Mrs. Carson made, to confuse people about her claims.
Postscript: Carson quotes Dr. DeWitt directly. Certainly he would be a key source on whether Ms. Carson misrepresented his words or his work. Unfortunately, I cannot find any indication that he is still living. I also have tried to track down others listed in the footnotes below. I found a listing for Dr. Robert Rudd as emeritus professor in the evolution division of the massive biological studies group at the University of California at Davis. However, a woman in the department office said their notes indicate he is now deceased.
When Carson wrote, these people were very much alive. Had she misrepresented their work and their words, it is likely they would have protested, and it’s possible they would have sued. I can find no evidence of any such protest, and there is no history of any such suits. Consequently, we must assume that the researchers cited by Rachel Carson agreed with her citations. I think Carson was faithful to DeWitt’s conclusions, but you can check for yourself [UPDATE, August 2012 - unfortunately the article has been moved behind a paywall; check the first page of the article here].
In contrast, Mr. Milloy now writes after these people are dead. It’s odd, troubling and a sign of warning, that Milloy claims to be collaborating with Dr. Gordon Edwards, since Edwards died in 2004 (of a heart attack while mountain climbing). Neither Edwards nor Rudd, nor DeWitt, nor most of the other sources Milloy cites, is alive to complain that he misquotes them or miscites their work, when he does (or if he does — he may be citing some of these people correctly).
Denialists love to make wild claims about Darwin and Einstein, in other science controversies. Milloy is nothing if not in denial, and that so many of his sources are dead, in a topic where there is so much live research, should certainly make one very wary of his claims about them and their research.
4. Rudd, Robert L., and Richard E. Genelly, Pesticides: Their Use and Toxicity in Relation to Wildlife, Calif. Dept. of Fish and Game, Game Bulletin No. 7 (1956), p. 57.